title: [Eremothecium ashbyii mutants resistant to 8-azaguanine. III. Nucleotide pyrophosphorylase activity of mutants with a varying degree of 8-azaguanine resistance].
abstract: Eremothecium ashbyii mutants resistant to low and high concentrations of 8-azaguanine (AZG), have been obtained. In low resistant mutants (10(-4) M AZG) isolated by one step selection, the activity of GMP- and AMP-pyrophosphorylases was decreased, as compared with the initial sensitive strain. The stepwise increase of the mutants resistance to AZG resulted in increasing of resistance to 8-azaadenine and decreasing of the activity of GMP-pyrophosphorylase, while this did not affect the level of AMP-pyrophosphorylase. Characteristics of the cross-resistance of mutant to purine analogues and the level of nucleotide-pyrophosphorylases activity were discussed in the light of their possible influence on riboflavin biosynthesis.
mesh_terms: D000228:Adenine Phosphoribosyltransferase / Q000235:genetics / Q000378:metabolism; D001203:Ascomycota / Q000235:genetics*; D001375:Azaguanine / Q000037:antagonists & inhibitors*; D004352:Drug Resistance, Microbial; D007041:Hypoxanthine Phosphoribosyltransferase; D009154:Mutation; D010430:Pentosyltransferases / Q000235:genetics / Q000378:metabolism; D004718:Saccharomycetales / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*
chemical_list: D010430:Pentosyltransferases; D000228:Adenine Phosphoribosyltransferase; D007041:Hypoxanthine Phosphoribosyltransferase; D001375:Azaguanine
vernacular_title: Mutanty Eremothecium ashbyii, ustoĭchivye k 8-azaguaninu. Soobshchenie III. Nukleotidpirofosforilaznaia aktivnost' mutantov s razlichnoĭ stepen'iu ustoĭchivosti k 8-azaguaninu.